As an attorney we use lawmatch.com, but I don't know if they do paralegals. Try your university's job board, most large firms post listings through the general job boards.

Hey I work for a recruitment firm and one of our divisions specializes in paralegal, JD, and attorney placements. I worked with the division for a few months last year.

While with some firms you do not need a paralegal certificate, some firms, some large firms, will not hire paralegals without a certificate, unless you have highly specialized skills, like an engineering degree, which can be useful considering some patent law reviews. It does not matter what you majored in considering your undergrad degree and some areas of law might suite you better than others. I was thinking, malpratice work if you have a nursing degree or some areas of tax law if you majored in business. It's not a bad thing to have but its not necessary, a la a MD to be a doctor